The present invention relates to a sample distributing method for measuring the steady quantity of the concentrations of chemical components of a sample, such as blood cells, blood plasma, blood serum or urine. 2. Description of the Related Art
Conventionally, this type of method is applied to a sample distributor which test a body fluid, such as blood cells, blood or urine, or blood transfusion, or a sample distributor which examines the quality of water in rivers, sewerage. A typical sample distributor of this type is provided with a probe capable of sucking and discharging a sample, and a syringe connected to the probe.
The portion extending from the pressure chamber of the syringe to the tip of the probe is filled with air as a pressure transmission medium. The pressuring/depressurizing action of the syringe will therefore act on the tip of the probe via air, so that a predetermined quantity of a sample (e.g., blood cells or urine) can be sucked or discharged from the tip of the probe.
Such a probe is cleaned with purging water in order to decontaminate an apparatus and eliminate a stuck sample.
In a test concerning blood transfusion, blood cells, blood plasma, blood serum or the like is used as a sample, and such samples of different physical properties are often tested at a time. In this respect, a conventional sample distributor uses two probes, which distribute blood cells and blood plasma or blood serum separately.
Sufficient sample purging has not however been done in the conventional sample distributing method, giving rise to a problem of infecting people with diseases, such as virus hepatitis and acquired immunodeficiency, through the samples remaining on or in the probes. The probes may be purged over a long period of time, which however requires a vast amount of purging water and is not so effective.
In addition, the conventional sample distributing method is designed on the premise that a sample is blood serum with low viscosity, relatively clean sewerage, or the like. In distributing samples with high viscosity which contain a surfactant such as blood cells or protein, therefore, air serves as a cushion against the distributing pressure, so that the quantity of the distributed sample will not be steady.
Further, the conventional sample distributing method hardly considers mutual contamination of sucked samples. In other words, in a clinical scientific test which has been the main flow of the conventional blood test, the difference between the lowest value and the highest value of each test item is about 100 fold. In a test of infectious diseases people are recently paying attention, to the difference between the lowest and highest values is approximately 100,000 to 1,000,000 fold. When this type of test is conducted by the conventional clinical scientific testing method, the number of false positive decisions would conspicuously increase due to the mutual contamination between samples.
Furthermore, as the number of probes is determined in accordance with samples with different physical properties in tests involving blood transfusion, the testing apparatus becomes inevitably large and the sample distributing method becomes complex, besides the considerable increase in false positive decisions in the tests of infectious diseases due to the mutual contamination between samples.